1. Field of the Invention
The present invention relates to a method for producing a water-resistant polarizing film in which organic dyes are oriented.
2. Description of the Related Art
A method for producing a water-resistant organic thin film by applying a solution including a multivalent metal salt or an amino compound salt (a compound having two amino groups or more in a molecular) onto an organic thin film including an organic dye (dye) containing a sulfonic acid group is well known (for example, Japanese Patent Application Laid-Open Publication No. JP 11-21538 A). The solution including an amino compound salt has lower toxicity than a solution including a multivalent metal salt and is easy to use. The water resistance of an organic thin film obtained by the use of an amino compound salt was, however, far lower than the one using a multivalent metal salt, which did not meet requirements for the applications of a polarizing film.